1. Technical Field
The present disclosure relates to switching modules including a switching element disposed at a conduction path to be opened or closed thereby.
2. Description of the Related Art
Conventionally, a switching module used for an inverter circuit connected to a motor generator has been employed. According to this switching module, the switching element turns the conduction path to be ON and OFF in response to a voltage difference between the reference terminal disposed at the end portion of one side of the conduction path and the control terminal of the switching element. For example, Japanese patent application publication laid-open publication number 2012-100461 discloses an inverter circuit connected to a motor generator as a traction motor mounted on a vehicle.
The inverter circuit includes switching elements of which drive circuits are disposed on the same semiconductor substrate. The switching elements that constitute the inverter circuit are mounted inside a cooling device and terminals such as gate terminal, etc. connected to the drive circuit are extended to the semiconductor substrate. These terminals are connected to the drive circuits disposed on the semiconductor substrate.
In the assembling process of the above-described inverter circuit, when the terminal of the switching element and the drive circuit are connected by soldering, assuming degradation of the semiconductor substrate occurs even though the switching elements themselves are normal, it is necessary to replace the semiconductor substrate together with the switching element. This is because the terminals of the switching element are soldered to the semiconductor substrate. However, when a configuration in which the terminals of the switching element is connected to the drive circuit via a connector and the connector contacts between the terminals and a conductor is employed, it is not necessary to replace the switching elements themselves mounted inside the cooling device when the semiconductor substrate is replaced.
However, in this case, conduction failure between the terminal and the conductor of the connector is likely to occur due to fretting corrosion. Specifically, when conduction failure occurs during the switching element turned ON, the switching element cannot be turned OFF. Therefore, controlling the opposite side of arm of the inverter to be ON, current that short-circuits the upper arm and the lower arm flows so that it is likely to degrade the reliability of the switching element.